Magnetoactive Plasma Research Articles

Collisional Mechanism of Expanding Wavenumbers Range of Weibel-Type Instability in Magnetoactive Plasma

For plasma with anisotropic velocity distribution of particles in the form of two counter-propagating bi-Maxwellian beams, including bi-Maxwellian plasma, in the presence of external magnetic field parallel to the beams, it is shown that in a wide range of parameters, particle collisions lead to the expansion of the wavenumbers range, generally towards the long-wavelength region, and weaken the conditions for the occurrence of the Weibel-type instability. In the specified expanded range, its growth rate, found by means of solving the dispersion equation for the wave vectors orthogonal to the external magnetic field, turns out to be less than or on the order of the frequency of particle collisions. Thus, in this range of parameters, the instability development and formation of large-scale magnetic turbulence in a plasma with weak particle collisions require the long-term injection of particles with anisotropic velocity distribution.

To plasma electrons motion theory in high-frequency fields

The article is dedicated to the kinetic theory of plasma, where the problem of interaction of high-frequency electric fields with weakly non-uniform plasma is investigated using kinetic equations with binary collision integrals for plasma particles. A new methodology for determining the expression of the averaged highfrequency pressure force is proposed based on solving the kinetic equation and using the method of successive approximations (separation of slow motions and fast oscillations) under the limiting conditions. An expression for the averaged quasi-potential force is derived based on the kinetic equation for the electron distribution function in weakly inhomogeneous magnetoactive plasma, taking into account electrons collisions with fixed ions and the presence of a longitudinally inhomogeneous high-frequency electric field using wellknown methods of theoretical and mathematical physics, such as successive approximations, averaging over the effective field oscillation period, and integration over trajectories. The amplitude of the field is a slowly varying function in both time and space coordinates. The obtained expression allows us to estimate the influence of collisions of plasma particles on the Miller force, and under limiting conditions it coincides with the known expressions for the high-frequency pressure force derived from the equation of plasma electrons motion in high-frequency fields. In all calculations, the contribution of the magnetic component of the electromagnetic field is neglected, which is quite justified for the longitudinal electric field.

Model expressions for refractive indices of electron waves in cold magnetoactive plasma of arbitrary density

Despite the undoubted importance of having fairly simple analytical expressions for the refractive indices of wave modes in a magnetoactive plasma, such expressions are known only in some particular cases. For electron waves with frequencies much higher than the lower hybrid resonance frequency, such an expression is known only for whistler waves in a dense plasma when the electron plasma frequency significantly exceeds the electron cyclotron frequency. In this Letter, we propose simple operational expressions for the refractive indices of all four electron modes in a magnetoactive plasma, namely, the fast magnetosonic, also called whistler mode, the slow extraordinary mode, the ordinary mode, and the fast extraordinary mode. The form of these expressions does not depend on the value of the ratio of plasma frequency to cyclotron frequency.

Collisional Mechanism of Expanding Wavenumbers Range of Weibel-Type Instability in Magnetoactive Plasma

Collisional Mechanism of Expanding Wavenumbers Range of Weibel-Type Instability in Magnetoactive Plasma

Surface wave propagation along a narrow transition layer in a slab Voigt geometry

The dispersion properties of electromagnetic surface waves, which propagate along a slab narrow transition layer separating two magnetoactive plasma uniform half spaces, are studied. Voigt geometry is considered, in which the waves propagate perpendicularly to an external uniform static magnetic field, which in turn is parallel to the interfaces between the plasmas and the transition layer. Electromagnetic power absorption within local resonances inside the transition layer is out of scope of the study. The influence of the plasma particle density profile smoothness on the surface wave dispersion properties is emphasized.

Dispersion Characteristics of Low-Frequency Electron Waves in a Magnetoactive Plasma of Arbitrary Density

The article studies waves in a collisionless magnetoactive plasma with frequencies much lower than the electron cyclotron frequency at an arbitrary ratio between the electron plasma and cyclotron frequencies. A general dispersion relation is obtained for the wave frequency as a function of the wave vector and the ratio of the plasma frequency to the cyclotron frequency. This relation is a bicubic equation with respect to frequency. Based on this equation, the existence domains of various wave modes depending on the specified parameter, their group velocity, polarization, and energy density are studied. Special attention is paid to low-frequency whistler waves in a low-density plasma, since, among the propagating wave modes existing in the specified range of parameters, whistler waves have the highest refractive index and play an important role in theresonant interaction of waves and particles.

Dispersion Characteristics of Low-Frequency Electron Waves in a Magnetoactive Plasma of Arbitrary Density

Dispersion Characteristics of Low-Frequency Electron Waves in a Magnetoactive Plasma of Arbitrary Density

Self-Guidance and Self-Focusing of Rippled Electromagnetic Radiation Pulse in High Density Magnetoactive Plasma


 Inside the plasma, when an intense rippled electromagnetic radiation pulse experiences self-focusing, one need to taking account of radial expansion in view of charge displacement due to ponderomotive force on electron and variation in the mass of oscillating electron under the influence of relativistic effect due to electromagnetic field. The extraordinary-mode (E-mode) propagation in a magnetoactive plasma, with stationary magnetic field, which is analogous to the wavering magnetic field of the electromagnetic radiation pulse, is the key feature for the self-guided propagation of rippling electromagnetic radiation pulse in magnetoactive plasma. If the condition for ultra-fast volume ionization is achieved, the radiation pulse itself can generate such a stationary magnetic field. It is demonstrated that external magnetic field affects the channels, causing them to bend. These effects cast new light on the phenomena of self-focusing of rippled electromagnetic radiation pulse. They raise the possibility of combining energy from several channels into one. It is found that the magnetic field strongly influences the plasma dynamic behavior and overall propagation of rippled electromagnetic radiation pulse.
 Keywords: Self-focusing, Self-guidance, Magnetized-plasma, Beam-propagation, Nonlinearity

A theoretic analysis of magnetoactive GES-based turbulent solar plasma instability

ABSTRACT A recently reported gravito-electrostatic sheath (GES) model is procedurally applied to study the turbumagnetoactive helioseismic oscillation features in the entire bi-fluidic solar plasma system. The bounded solar interior plasma (SIP, internally self-gravitating), and the unbounded solar wind plasma (SWP, externally point-gravitating) are coupled through the interfacial diffused solar surface boundary (SSB) due to an exact gravito-electrostatic interplay. A numerical platform on the developed theoretic formalism reveals the evolution of both dispersive and non-dispersive features of the modified GES mode fluctuations in new parametric windows. Different colourspectral profiles exhibit important features of the GES-based SIP–SWP perturbations elaborately. It is illustratively shown that the thermostatistical GES stability depends mainly on the radial distance, magnetic field, equilibrium plasma density, and plasma temperature. We see that their dispersive features are more pertinently pronounced in the self-gravitational domains (SIP) than the electrostatic counterparts (SWP). Besides, different characteristic parameters with accelerating (or decelerating) and stabilizing (or destabilizing) effects influencing the entire solar plasma stability are illustratively portrayed. We speculate that, in the SIP, the long-wave (gravitational-like) helioseismic fluctuations become highly dispersive showing more propagatory nature than the shorter ones (acoustic-like). The short waves show more propagatory propensity than the longer ones in the SSB and SWP regime. The reliability of our proposed investigation is bolstered along with the tentative applicability and future scope in light of the current solar observational scenarios, such as SOHO, STEREO, SDO, PSP, and SolO.

Some Variations of the Parameters of the Magnetoactive Plasma during the Transportation by Gigantic Convective Cells

Some Variations of the Parameters of the Magnetoactive Plasma during the Transportation by Gigantic Convective Cells

The influence of an external magnetic field on cold plasma oscillations

For a system of equations describing one-dimensional nonlinear oscillations in a magnetoactive plasma, we study the effect of a constant magnetic field on the breaking of oscillations. For the nonrelativistic case, a criterion for the formation of a finite-dimensional singularity is obtained in terms of the initial data. It is shown that the enhancement of the magnetic field basically leads to an expansion of the class of initial data providing the global smoothness of the solution. The nature of the singularities of the solutions is illustrated by numerical examples.

Non-planar magnetoactive GES-based solar plasma stability

A laboratory plasma-wall interaction-based astrophysical gravito-electrostatic sheath (GES) model is methodologically applied to study the dynamic stability of the magnetoactive bi-fluidic solar plasma system in the presence of turbulence effect. The spherically symmetric GES-model formalism couples the solar interior plasma (SIP, internally self-gravitating, bounded) and the solar wind plasma (SWP, externally point-gravitating, unbounded) through the diffused solar surface boundary (SSB). A normal spherical mode ansatz results in a generalized linear quadratic dispersion relation depicting the modal fluctuations on both the SIP and SWP scales. A constructive numerical platform reveals the evolution of both dispersive and non-dispersive modal features of the modified-GES mode excitations. The reliability of the derived non-planar dispersion laws is concretized with the help of an exact analytic shape matching the previously reported results founded on the plane-wave approximation. It is found that the thermo-statistical GES stability depends mainly on the magnetic field, equilibrium plasma density, and plasma temperature. It is speculated that the dispersive features are more pronounced in the self-gravitational domains against the electrostatic ones. The magneto-thermal interplay introduces decelerating (accelerating) and destabilizing (stabilizing) influences on the SIP (SWP), and so forth. At last, we briefly indicate the applicability of the proposed analysis to understand diverse helioseismic activities from the collective plasma dynamical viewpoint in accordance with the recent astronomical observational scenarios reported in the literature.

The interplay of regularizing factors in the model of upper hybrid oscillations of cold plasma

A one-dimensional nonlinear model of the so-called upper hybrid oscillations in a magnetoactive plasma is investigated taking into account electron-ion collisions. It is known that both the presence of an external magnetic field of strength B0 and a sufficiently large collisional factor ν help suppress the formation of a finite-dimensional singularity in a solution (breaking of oscillations). Nevertheless, the suppression mechanism is different: an external magnetic field increases the oscillation frequency, and collisions tend to stabilize the medium and suppress oscillations. In terms of the initial data and the coefficients B0 and ν, we establish a criterion for maintaining the global smoothness of the solution. Namely, for fixed B0 and ν>0 one can precisely divide the initial data into two classes: one leads to stabilization to the equilibrium, and the other leads to the destruction of the solution in a finite time. Next, we examine the nature of the stabilization. We show that for small |B0| an increase in the intensity factor first leads to a change in the oscillatory behavior of the solution to monotonic damping, which is then again replaced by oscillatory damping. At large values of |B0|, the solution is characterized by oscillatory damping regardless of the value of the intensity factor ν.

Low Frequency Oscillations of Plasma Injected into an Open Magnetic Trap from an Independent Ultrahigh Frequency Source

Methods of plasma heating by electromagnetic waves, interaction of electro-magnetic waves with magnetoactive plasma, plasma turbulence and transport processes are investigated in the trap of the linear plasma device OMT2. An ultrahigh frequency (UHF) contactless method is used to fill the open magnetic trap by plasma. We propose a new method of open magnetic trap filling with plasma whereby plasma is injected in the trap along the magnetic field from an independent stationary UHF source. The source is located outside the trap and plasma formation in it takes place in the strongly nonuniform magnetic field, in the electron cyclotron resonance (ECR) regime by means of the UHF power. In this paper we study the efficiency of open magnetic trap filling by plasma and plasma low frequency (LF) oscillations in the trap.

Ionospheric total electron content (TEC) above Ecuador

The equatorial ionosphere over the Ecuadorian territory has not been previously studied, although there are some studies in other equatorial geographical positions, local research is required to characterize the ionospheric magnetoactive plasma in this region.In this study, for the first time in Ecuador, using pseudophase and pseudorange data from the satellite signals of the GPS system, detected at the Riobamba-Ecuador (RIOP) station, the Total Electronic Content (TEC) is estimated in the period between the years 1999 and 2019. The TEC values and their daily, weekly, monthly and annual variation are calculated and compared with the observed data of the IGS network (International GNSS Service). The fit of the observed series with the series of the dispersive model has a goodness of fit of 0.88, which is quite acceptable. The adjustment can be improved by incorporating data from new local stations, as well as instrumental errors and delays and in the received signals, all of which were not considered in the present work.

On the Breaking of a Slow Extraordinary Wave in a Cold Magnetoactive Plasma

On the Breaking of a Slow Extraordinary Wave in a Cold Magnetoactive Plasma

Simulation of Plasma Emission in Magnetized Plasmas

Abstract The recent Parker Solar Probe observations of type III radio bursts show that the effects of the finite background magnetic field can be an important factor in the interpretation of data. In the present paper, the effects of the background magnetic field on the plasma-emission process, which is believed to be the main emission mechanism for solar coronal and interplanetary type III radio bursts, are investigated by means of the particle-in-cell simulation method. The effects of the ambient magnetic field are systematically surveyed by varying the ratio of plasma frequency to electron gyrofrequency. The present study shows that for a sufficiently strong ambient magnetic field, the wave–particle interaction processes lead to a highly field-aligned longitudinal mode excitation and anisotropic electron velocity distribution function, accompanied by a significantly enhanced plasma emission at the second-harmonic plasma frequency. For such a case, the polarization of the harmonic emission is almost entirely in the sense of extraordinary mode. On the other hand, for moderate strengths of the ambient magnetic field, the interpretation of the simulation result is less clear. The underlying nonlinear-mode coupling processes indicate that to properly understand and interpret the simulation results requires sophisticated analyses involving interactions among magnetized plasma normal modes, including the two transverse modes of the magneto-active plasma, namely, the extraordinary and ordinary modes, as well as electron-cyclotron-whistler, plasma oscillation, and upper-hybrid modes. At present, a nonlinear theory suitable for quantitatively analyzing such complex-mode coupling processes in magnetized plasmas is incomplete, which calls for further theoretical research, but the present simulation results could provide a guide for future theoretical efforts.

Численное моделирование наземного распределения напряженности поля бортового низкочастотного передатчика в ионосфере.

Projects of active experiments in the ionosphere and the magnetosphere of the Earth and planets often include powerful low-frequency transmitters installed on-board of a spacecraft. Such sources are very effective, but their radiation is extremely heterogeneous in space because of the anisotropy of the ionospheric plasma due to the presence of the magnetic field of the Earth. This paper is devoted to numerical modeling of a distribution of the wave field strength near the Earth surface. The work examines a specific active wave experiment with a 20 m loop as a transmitting antenna. The satellite is assumed to orbit with an inclination of 82.5 degrees at an average altitude of 1000 km. All calculations are performed in linear approximation using the cold magneto-active plasma model. The computation model uses ray approximation everywhere except for the highly heterogeneous lower ionosphere, where a full wave equations set is applied. It is shown that the maximum magnetic field value is decreased with increasing of the geomagnetic latitude value and the strength range is 1… 2 nA/m for frequency 10 kHz and loop current 100 A. The magnitude of the vertical component of the electric field lies in the range of 0.4 ... 0.8 μV/m. An average Doppler frequency shift is equal to ~0.4 Hz. A comparison is made between the data of the numerical experiment and the results of simple estimations of the values of the magnetic field strength at the maximum of the ground distribution.

Analytical Model of a Magnetopause in a Multicomponent Collisionless Plasma with a Kappa Energy Distribution of Particles

We propose an analytical model for a distributed current sheet with a variable profile that separates two regions of anisotropic collisionless plasma with different magnetic fields and different effective temperatures of the kappa energy distributions of electrons and ions. The model also admits the presence of several ion components with different effective temperatures and spatially separated localized countercurrents of each of these components. We demonstrate the change in the characteristics of the current sheet when going from a Maxwellian to a kappa distribution, which takes into account the presence of a power-law spectrum of energetic particles typical of a nonequilibrium magnetoactive plasma. The theory developed allows us to carry out for the first time analytical modeling of such current configurations in both laboratory and cosmic plasmas, e.g., in planetary magnetopauses, coronal loops, and stellar wind with magnetic clouds.

HIGHER RADIAL MODES OF AZIMUTHAL SURFACE WAVES ABOVE THE UPPER-HYBRID FREQUENCY IN CYLINDRICAL WAVEGUIDES PARTIALLY FILLED BY PLASMA

Azimuthal surface waves (ASWs) are known to be eigen waves of cylindrical metal waveguides partially filled by magnetoactive plasma. Zeroth radial modes were under study earlier. Their dispersion properties are known to be significantly influenced by the plasma column properties: its particle density, external axial static magnetic field, geometric dimensions, – rather than properties of the dielectric layer which separates the plasma column from the metal wall. Application of higher order ASWs in the low-frequency range was shown earlier to make it possible to get advantage of exciting ASWs with higher frequency than in the case of zeroth order ASWs without no change in the waveguide design. The present study generalises those investigation for the case of the waves above the upperhybrid frequency.